Although rare, Irish harpsichords closely resemble contemporary instruments made in London. This example, for instance, probably built in the mid 1770s, is made largely of oak and veneered in panels of mahogany. It has a compass of 5 octaves and 1 tone, F1, G1 to g3 (omitting F♯1). The four hand stops control 2 sets of 8ft strings, a lute and a buff stop. The plectra of the first unison, originally of soft leather, were changed to quill at the end of the 18th century. Like English harpsichords, the natural touchplates are of ivory and the sharp blocks are capped with a thin strip of ebony. This instrument is fitted with a mechanism for enabling crescendo effects, known as a Venetian swell. Patented by Burkat Shudi in 1769, the device consists of a set of louvers fitted over the soundboard, which can be opened and closed using a knee lever situated under the treble end of the keyboard.